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In a stream hosted earlier this week by The New Stack, Kelsey Hightower, developer advocate, Google Cloud Platform, talked about the serverless and security aspects of Kubernetes. The stream was from KubeCon + CloudNativeCon 2018.

What are you exploring right now with respect to serverless?

There are many managed services these days. Database, security etc is fully managed i.e., serverless. People have been on this trajectory for a while if you consider DNS, email, and even Salesforce. Now we have serverless since managed services are ‘eating that world as well’. That world being the server side world and related workloads.

How are managed services eating the server side world?

If someone has to run and build an API, one approach would be to use Kubernetes and manage the cluster and build the container, run it on Kubernetes and manage that. Even if it a fully managed cluster, you may still have to manage the things around Kubernetes.

Another approach is to deal with a higher form of extraction. Serverless is coupled often with FaaS (Function as a Service). There are a lot of abstractions in terms of resources, i.e., resources are abstracted more these days.

Hightower talks about a test: “If I walk up to a platform and the delta between me and my code is short, you’re probably closer to the serverless mindset.” This is different from creating a VM, then installing something, configuring something, and then running some code—this is not really serverless.

Serverless in a Kubernetes context

The point of view should be—can we improve the experience on Kubernetes by adopting some things from serverless? You can add a layer that does functions, so developers can stop worrying about containers and focus on the source. The big picture is—who autoscales the whole cluster?

Kubernetes and just an additional layer can’t really be called serverless but it is going in that direction. Over time, if you do enough so that people don’t have to think about or even know that Kubernetes is there, you’re getting closer to being truly serverless.

Security in Kubernetes

Hightower loves the granular controls of serverless technologies.

Comparing the serverless security model to other models

For a long time in the industry, companies have been trying to do a least privilege approach. That is, limiting the access of applications so that it can perform only a specific action that is required. So if one server is compromised and it does not have access to anything else, then the effects are isolated.

The Kubernetes approach can be different. The cloud providers try to make sure that all the credentials needed to do important things are segmented from VM, cloud functions, app engine or Kubernetes. Imagine if Kubernetes is where everything lives free. Instead of one machine being taken down, it is now easier for the whole cluster to be taken down in one shot. This is called ‘broadening the blast radius’. If you have Kubernetes and you give it keys to everything in your cluster, then everything is compromised when the Kubernetes API is compromised. Having just one cluster trades off on security.

Another approach to serverless security

A different security model is where you explicitly give credentials that may be needed. So there is no scope to ask for any credentials etc, it will not be allowed. You can also go wrong on a serverless but the system is better defined in ways that it limits what can be done. It’s easier to secure when the attack surface is smaller.

For serverless security the same principles from engineering techniques apply, you just have to apply it to these new platforms. So you just need knowledge about what these new platforms are doing. The same principles apply, admins just have a different layer of abstraction that they may add some additional security to.

The more people use the system, more flaws are continuously found. It takes a community to identify flaws and patch them. So as a community is more mature, dedicated security researchers come up and patch flaws before they can be exploited.

To see the complete talk where Hightower talks about his views on what he is working on, go to The New Stack YouTube Channel.

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